The Biocurrents Research Center, an NCRR resource, specializes in studying the transport of ions and nnolecules across the plasma membrane of cells. A particular expertise lies in the application of electrochemical microsensors to describing diffusion within the extended boundary layer and thus defining a chemical signature of the cell state. Microsensors are non-invasive, potentiometric and amperometric, of micron proportions, and normally operate in a modulation format. Measurement of molecules and ions can be made from identified single cells in heterogeneous populations, and can sample from specific regions of cells. Slow and non-electrogenic transport events can be followed. Modifying the microelectrode and its operation allows the detection of millisecond channel events, non-invasively, on the basis of ion diffusion from the source on the cell membrane. Proposed core objectives for the next cycle are to: further develop channel detection and analysis from single cells alongside feedback position control;develop multianalyte sensors to facilitate stochiometric analysis of transporters and concentric electrode designs to regulate the fluid micro-volumes surrounding sensors;develop low light imaging techniques, targeting functionalized fine particles and plasmid reporters, to monitor the chemical signatures within the immediate extracellular and intercellular space;simplify and automate electrochemical platforms for clinical applications in ovarian cancer and reproductive medicine. The Core Objectives are chosen to provide new methodologies to the Driving Biomedical Projects which span basic biomedical interests in transporters and cellular function, to clear clinical questions in cellular and tissue pathology. In keeping with the goals of an NIH resource, we also offer an extensive collaborative and service component. The large majority of our user group receives funds from the NIH but we also host interests from other federal agencies, such as the NSF and DoD. These activities along with our outreach through training and support of off-campus research initiatives will be enhanced through the next cycle.